Armorers display considerable skill, ingenuity and manual dexterity in the assembly of firearm mechanisms, which are often complex and require the manipulation of relatively small parts in confined workspaces within the receivers of shotguns and rifles as well as within the frame of a pistol. Spring biased parts, such as detents, present a particular challenge because force must often be maintained on the parts to keep the biasing spring compressed while other parts are manipulated. Additionally, unless laterally supported, long springs buckle under the slightest compressive load, thereby complicating the assembly process further. There is clearly an opportunity to provide design enhancements of parts which provide advantages to assembly and disassembly of firearm mechanisms.